Receptacle



G. E. BLINN Dec. 7, 1943.

RECEPTACLE Filed June l0, 1942 2 Sheets-Sheet 2 lNv TOR l @mol/4ATTORNEYS Patented Dec. 7, 1943 UNITED STATES PATENT OFFICE RECEPTACLEGlenn E. Blinn, Harrington Park, N. J.

Application June 10, 1942, Serial No. 446,455

16 Claims. (Cl. 173-328) This invention relates to electricreceptaclesoi.' the type which includes terminals engageable by theprongs of a plug inserted into holes in the receptacle* for the purposeof connecting together conductors which are connected, respectively, tothe terminals and the prongs. More particularly, the invention isconcerned with a receptacle provided with novel safety means whichprevent accidental contact with the live parts of the receptacle andalso serve to suppress the arc which may be formed when a heavy ilow ofcurrent through the conductors is broken by withdrawal of the plug fromthe receptacle.

The receptacle of the invention resembles in many respects thatdisclosed in my Patent No. 2,155,925, April 25, 1939, but is superiorthereto in that it is of simpler construction and, therefore, lessexpensive to manufacture and, in addition, it is more nearly positive inaction and provides a greater degree of safety.

The new receptacle may be constructed to receive any standard plughaving two or more connection prongs, such, for example, as an ordinaryplug having two prongs lying parallel, a polarized plug having twoprongs lying at an angle to one another, or a three-prong plug for usein a system having a ground wire. In al1 constructions, the receptacleincludes a door member which normally closes the holes through which theprongs of the plug are inserted to make contact with the terminals andthe door is normally locked in closing position. When the prongs of theplug are simultaneously introduced into the holes and moved inward, oneprong rst unlocks the door member and shortly thereafter the otheroperates means by which the door member is moved away from the positionin which it closes the holes. The ends of the prongs may .then movebeyond the door to the terminals. When the plug is removed, the doormember is returned automatically to closing position and again locked inthat position.

The means by which the door is moved to and from closing position are ofsuch construction that the movement imparted to the door by the actionof the prong may be greater than the dimension of that prong in thedirection of movement of the door. This makes it possible to employ adoor which closes the holes leading to the terminals with a substantialoverlap, so that when the door is in closing position, it cannot bepried open by a tool inserted through one of the holes. The door movingmeans do not act directly on the door but operate through a spring, sothat if the means are actuated before the door is unlocked, the movementof the means will be taken up by flexure of the spring and none of theparts of the receptacle will be injured.

For a better understanding of the invention, reference may be had to theaccompanying drawings in which Fig. 1 is a sectional view of one form ofthe new receptacle on the line I-I of Fig. 2;

Fig. 2 is a sectional view on the line 2-2 of Fig. 1;

Fig. 3 is a sectional view on the line 3--3 of Fig. 1;

Figs. 4 and 5 are views similar to Figs. 2 and 3, respectively, showingthe action of the parts upon insertion of the prongs of a plug;

Fig. 6 is a perspective view of the door member and its locking andoperating means in disassembled relation;

Fig. '7 is a view in elevation of the face of a modied form of thereceptacle for use in a threewire system.

Fig. 8 is a sectional view of the modied form of the receptacle on theline 8-8 of Fig. 9;

Fig. 9 is a sectional view on the line 9-9 of Fig. 8;

Fig. 10 is a plan view of the door member used in a receptacle of Figs.7 to 9, inclusive;

Fig. 11 is a view similar to Fig. 7 of a polarized receptacle of the newconstruction;

Fig. l2 is a sectional view of the polarized receptacle on the line|2-l2 of Fig. 13;

Fig. 13 is a sectional view of the receptacle on the line |3-I3 of Fig.12; and

Fig. 14 is a plan view of the door member employed in the receptacle ofFig. 11.

Referring to the drawings,the receptacle shown in Figs. 1 to 6,inclusive, includes a housing formed of two parts 20a, 20h made ofinsulating material. Part 20a has an opening 2l at one end through whichextends an electric cord 22 containing a pair of insulated conductors23, 24 connected by screws 25 to contact terminal springs 26. Theterminals are secured to the inner face of the housing member 20a andextend into the hollow interior of the housing member 20h. The members20a and 20h are secured together in any suitable manner and the member26h has a flat front end 21 through which are formed holes 28 inalignment with the spring terminals. The holes are shaped to receive theprongs 29 of a plug 30 of the usual construction, the prongs beingconnected to conductors in a cord 3l, as is customary.

The 'member 20a is provided with a central hollow extension 32 ofinsulating material which flts into member 28h and has a portion 32alying between terminals 26. Between the free end of portion 32a and theinner faces of projections 33 from the inner surface of end wall 21 `ofthe housing member h is a door member 34. In the construction shown, thedoor is a plate of insulating material of generally oblong shape havinga width substantially greater than` `the width of the individual prongsof the plug to be used with the receptacle and a. length substantiallygreater than the distance between the centers of the prongs. The doormember is provided with notches 35 in its long sides near one end and anopening 36 is formed through the door member beyond the notches towardthe other end, the opening being slightly larger than the cross-sectionof one of the prongs. Just beyond the opening 36 is another opening 31for a purpose to be described. The distance between the end wall 38 ofthe door member and the adjacent wall of the opening 36 is slightly lessthan the distance between the opposed faces of the prongs of the plug.

'I'he door member is provided with a latch taking the form of a spring39 seated in a recess in extension 32 of housing member 20a. One end 40of the spring overlies the door member, the extreme end portion 40hentering one of the notches 35 in the door member, when the latter is innormal closing position. Immediately above the portion 40a, the springis provided with a curved cam surface 4I which lies in the path ofmovement of a prong entering one of the holes 28. As the prong movesthrough the hole, it engages the cam surface and exes the spring so thatits end portion 40h moves out of the notch 35 and the door is released.

The door member is movable endwise by means which include a shaft 42seated in notches in the end Wall of the extension 32 and lying parallelto the door member. The shaft is provided with an arm 43 which entersthe opening 31 in the door member and it also has an arm 44 ofconsiderable breadth which normally extends part Way across the secondhole 2B. A spring 45 is seated in the interior of the portion 32a ofextension 32 and this spring has a double end, both portions of whichextend through opening 31 through the door. One part 46 of the doubleend of the spring bears against the'arm 43 on shaft 42 and normallyforces the arm against one wall of opening 31 to hold the door inclosing position with solid parts thereof in front of both holes 28. Theother end portion 41 of the double end of the ,spring bears against theopposite wall of opening 31. In the normal position of the parts, thearm 44 on shaft 42 lies inward from the face 21 of the receptacle aslightly greater distance than the cam surface 4I on latch spring 39.

When a connection is to be made at the new recepetacle, the prongs of aplug are inserted into the holes 28 and, as the prongs move inward, oneprong strikes cam surface 4l on the latch and ilexes the latter to movethe end 40h out of notch 35 on the door member and release the latter.Shortly thereafter, the other prong strikes the arm 44 on shaft 42 androcks the shaft. In this movement of the shaft, the arm 43 thereon actson portion 46 of spring 45 to ilex the double end of the spring and thataction causes the end 41 of the spring to move the door member endwise.The extent of movement is such that the end wall 38 of the door membermoves entirely across one of the holes 28 and the opening 36 through thedoor member moves into alignment with the other pass through the openingin the door until b oth prongs engage the contact springs 26.

It will be observed that arm 43 on shaft 42 is considerably longer thanarm 4'4 and that arrangement is advantageous for following reasons. Whena prong enters the hole in which arm 44 is exposed and engages andswings the arm out of the path of the prong, the arm is moved by anamount not greater than the thickness of the prong and, therefore, notgreater than the dimension of the hole at right angles to the axis onwhich the arm swings. If arms 43 and 44 were of the same length, theendwise movement of the door produced bythe action of the prong on arm44 would, therefore, be not greater than the thickness of the prong orthan the dimension of the hole in the direction of movement of the door.Accordingly, in a construction in which the arms are equal in length,the door in its closing position cannot overlap the walls of the hole,since otherwise the insertion of a prong in the hole would not produce asufcient movement of the door to open the hole completely. 'I'he endwall 38 of the door might lie flush with one wall of one hole 28 and theremote wall of opening 36 through the door might lie flush with thecorresponding wall of the other hole 28, but that arrangement, which` isthe best obtainable under the conditions specified, would not besatisfactory, because it would be possible to insert a tool through oneof the holes and force it past the end of the door or into opening 36and pry the door aside. The tool might then be forced inwardly intocontact with a terminal 26.

If arm 43 is longer than arm 44, as in the construction described, themovement imparted to the door member by the swinging of arm 44 by meansof a prong inserted through one of the holes 28 may be substantiallygreater than the thickness of the prong and greater than the di mensionof the hole in the direction in which the door is moved. The door may,therefore, be so constructed that, in its closing position, solidportions thereof will close the holes with a substantial overlap, asshown in Fig. 2. Such an overlap makes it impossible to pry the dooropen by a tool inserted through either of holes 28 and thus the use of adoor arm 43, which is longer than the prong arm 44, makes the receptaclecompletely safe.

Y Arm 43 does not act directly on the door member to effect movement ofthe latter away from closing position, but, instead, the movement of arm43 flexes the double end of spring 45 and end portion 41 of the springmoves the door member to open position. Accordingly, if a tool or oneprong only of a plug is inserted through hole 28 and engages and swingsarm 44, the door member will remain locked in position by latch 33 andthe movement of arm 44, shaft 42, and arm 43 will merely cause iiexureof the double end of the spring. Thus, under the conditions mentioned,no damage will be done to the door moving means and the door will not bemoved to expose a live terminal.

The receptacle shown in Fig. 7 is of the threepole type and includes twolive terminals which may be reached through openings 48 lying at anangle toone another and a grounded terminal in line with a` thirdopening 49. In this receptacle,

the openings 48 leading to the live terminals are normally closed by adoor 50 in the form of a plate with its ends 5l lying at an angle to oneanother corresponding to the angle between openings 48. A notch 52 isformed in one side `through the door, the longitudinal axis of theopening lying parallel to adjacent end I of the door. The door is alsoprovided with an opening 54 through which may extend the double end ofspring 55 similar in form and mounting to spring 45. A shaft 56 isjournalled in the end of an extension from one of the housing members ofthe receptacle and lies parallel with the door. The shaft is providedwith an arm 51, which extends partly across one of the holes 48, andcarries another arm 58 which extends through opening 54 in the doormember and lies between a wall of the opening and one of the endportions of the spring 55.

With this construction, on insertion of the prongs of a plug into holes48, one prong rst engages the latch 53 and releases it from the notch 52in the door member. Immediately thereafter, the other prong strikes arm51 on shaft 56 and rocks the shaft, so that its end 58 causes flexure ofthe double end of spring 55 and this, in turn, causes endwise movementof the door member. In such movement, one end 5l of the door membermoves to clear one hole 48 in the receptacle, while the opening 53amoves into registry with the other opening. The prongs may then passbeyond the door member and make contact with the live spring terminals.In this receptacle, it is not necessary to provide any safety meansnormally closing the hole 49, since that hole leads to a groundedterminal.

'Ihe receptacle shown in Figs. 11 to 14, inclusive, is of the polarizedtype and includes a pair of terminals lying with their axes at rightangles. Access to these terminals is normally cut off by a door 59pivoted at 60 on a pin 6I seated in extension 62 from one of the housingmembers of the receptacle. The door has an opening 63 therethrough andthrough part 63a of the opening extends the double end of spring64seated in extension 62. A shaft 65 is mounted for rocking.

movement in the end of the extension and the shaft has an arm 66 lyingacross one hole 61 leading to one of the spring terminals 68. The

shaft is also provided with an arm 69 lying between one Wall of opening63a and one end portion of spring 64. A latch spring seated in theextension 62 normally lies within a notch 1l in the side of the doormember.

With this construction, the spring 64 normally holds the door memberclosed, that is, with solid portions thereof aligned with holes 61. Arm66 on shaft 65 is accessible through one of the holes and latch 10 isaccessible through the other. On insertion of the prongs of the plug,latch 10 is first released by one prong and, thereafter, the other prongengages arm 66 on shaft 65 and causes the shaft to swing. In thismovement, arm 69 on the shaft engages one portion of the double end ofspring 54 and flexes that end of the spring to cause the spring to swingthe door member on its pivot until the wall 12 thereon has passed beyondone opening 61 `and the part 63h of opening 63 through the door memberhas been brought into alignment with the other hole 61. The prongs ofthe plug may then continue their movement inward to the spring terminalswith- I out interference by the door member. Normally the door member isheld in closing position by spring 64 against a stop pin 13.

In all forms of the new receptacle, the holes through which the prongsof, the plug are inserted to make engagement withthe live terminals arenormally closed by the door member and insertion of one plug prong or atool through either hole will not move the door member. If the prong isinserted through the hole through which the latch is accessible, theengagement of the latch by the prong will release the door member butwill not produce any movement thereof. Similarly, if the prong isinserted through the other hole, it may engage an arm on the shaft ofthe moving means and cause the shaft to swing and the other arm thereonto flex the double ended spring. The flexure of the spring, however,will not cause any movement of the door member because the latch has notbeen released. Accordingly, there is little likelihood that accidentalcontact will be made with the live terminals of the receptacle and itwould be difficult for a child, for example, to reach the live terminalsbecause both the latch and the door moving means must be actuated beforethe door is moved to open position. At the same time, insertion of aplug into the new receptacle or removal of a plug therefrom requiresonly a straight line movement of the plug, so that in manner of use, thenew receptacle is the same as one of conventional construction.

The construction described permits the use of a relatively stiff springfor maintaining the door in closed position and, consequently, when theplug is removed, the door is moved toward closed position quickly andwith considerable force. Receptacles of this general type are frequentlyused in circuits in which the currents owing are such that, with theordinary receptacle and plug, the breaking of a circuit by removal of aplug results in an arc which may extend from the live terminal outthrough the end of the receptacle. Under some conditions, the formationof such an arc may present a considerable lre hazard, as, for example,when the receptacle is located in a baseboard near inflammable curtains.With the new'receptacle, the removal of the plug causes the door to bemoved rapidly to closed position, with the result that any arc that mayform is instantly suppressed and the hazard is avoided.

The new receptacle has less parts than the receptacles disclosed in mypatent and,` in addition,

the parts are of simpler construction and easier and less expensive tomake. Also, assembly of the new receptacle is easier. The operatingparts of the new receptacle are more rugged than those of thereceptacles of the patent, and this insures that the new receptacle willhave a longer life and be less likely to break down in service. Also,the use of the spring as the means through which force is applied to thedoor to open the latter protects the receptacle against injury, sincethe moving means can be actuated, even though the door is latchedagainst movement, without any injury being done to the parts.

I claim:

l. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut olf access to the terminals, a latch normallylocking the door member in closing position and releasable through oneof the holes, spring means tending to resist movement of the door memberawayfrom closing position, and means accessible through another hole andoperable upon the spring means to cause the latter, upon release of thelatch. to move the door member away from closing position.

2. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut off acce'ss to the terminals, a latch normallylocking the door member in closing position and releasable through oneof the holes, spring means tending to resist movement of the'door memberaway from closing position, and means accessible through a second holeand operable upon the spring means to cause the latter, upon release ofthe latch, to move the door member away from closing position a distancegreater than the dimension of the second hole in the'direction of suchmovement of the door member.

3. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut oi access to the'terminals, a latch normallylocking the door member in closing position and releasable through oneof the holes, spring :means tending to resist movement of the doormember away from closing position, and a swinging element accessiblethrough another hole and operable upon the spring means to cause thelatter. upon release of the latch, to move the door member from closingposition.

4. In an electric receptacle having at least a pair of terminals and'holes into which the con. nection prongs of a plug may be inserted tomake contact with the terminals, the combination of a door membernormally closing the'holes to cut oi access to the terminals, springmeans tending to resist movement of the door member away from closingposition, and means accessible through another hole and operable uponthe spring means to cause the latter to move the door member away fromclosing position.

5. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut yoi access to the terminals, spring meanstending to resist movement of the door member away from closingposition, and means accessible through a second hole and operable uponthe spring means to cause the latter to move the door member away fromclosing position a distance greater than the dimension of the secondhole in the direction of such movementr of the door member.

6. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to'make contact with the terminals, the combination of a door membernormally closing the holes to cut oil access to the terminals, springmeans tending to resist movement of the door member away from closingposition, and a swinging element accessible through another hole andoperable upon the spring means to cause the latter to move the doormember away from closing position.

7. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut off access to the terminals and movable in aplane away from closing position to afford such access, spring meansresisting movement of the door member away from closing position, and anelement mounted for swinging movement about an axis parallel 'to theplane of movement of the door member and Operable through one of theholes to act upon the spring means to cause the latter to move the doormember away from closing position.

8. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a. door member normallyclosing the holes to cut off access to the terminals and movable in a.plane away from closing position to aord such access, spring meansresisting movement of the door member away from closing position. ashaft mounted for oscillation on an axis parallel to the plane ofmovement of the door member, an arm on the shaft engageable through oneof the holes to rock the shaft, and a second arm carried by the shaftand operable upon the rocking of the latter to move the door member awayfrom closing position.

9. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut ofi access to the terminalsv and movable in aplane away from closing position to afford such access, spring meansresisting movement o1' the door member away from closing position, anelement mounted vfor swinging movement about an axis parallel to theplane of movement of the door member and operable through one of theholes to move the door member away from closing position, and a latchnormally locking the door member in closing position and releasablethrough a second hole.

10. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut oli access to the terminals and movable in aplane away from closing position to aiord such access, spring meansresisting movement of the door member away from closing position, andmeans accessible through another hole and operable upon the spring meansto cause the latter to move the door member away from closing position.

l1. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs oi a plug may be inserted to makecontact with the terminals, the combination of a door member normallyclosing the holes to cut oil access to the terminals, a spring having aportion engaging the door member, and means' accessible through one ofthe holes and engaging another portion of said spring, said means beingoperable to-flex said spring to cause the rst portion thereof to movethe door inember away from closing position, said second portion of thespring normally acting through said means to maintain said door memberin closed position.

12. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member pivoted forswinging movement and normally closing the holes to cut off access tothe terminals, a spring tending to resist movement of the door memberaway from closing position, and means accessible through one of theholes to act upon the spring to cause the latter to move the door memberaway from closing position.

13. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member pivoted forswinging movement and normally closing the holes to cut off access tothe terminals, a latch normally locking the door member in closingposition and releasable through one of the holes, and means accessiblethrough another hole and operable upon release of the latch to swing thedoor member away from closing position.

14. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member pivoted forswinging movement and normally closing the holes to cut oi access to theterminals, a latch normally locking the door member in closing positionand releasable through one of the holes, means accessible throughanother hole and operable upon release of the latch to swing the doormember away from closing position, and spring means tending to resistmovement of the door member away from closing position. f

15. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a door member pivoted forswinging movement and normally closing the holes to cut 01T access tothe terminals, a latch normally locking the door member in closingposition and releasable through one of the holes, means tending toresist movement of the door member away from closing position, and meansaccessible through a second hole and operable through the spring means,upon release of the latch, to move the doormember away from closingposition.

16. In an electric receptacle having at least a pair of terminals andholes into which the connection prongs of a plug may be inserted to makecontact with the terminals, the combination of a. door member normallyclosing the holes to cut off access to the terminals, a spring having aportion seated in a recess in the door member and serving as a latch tohold the door member Y in closing position, said portion of the springbeing accessible through one of the holes for lexure to release the doormember, a swinging element accessible through another hole, and aspringhaving a portion engaging the door member and another portion actingthrough the swinging element to resist movement of the door member awayfrom closing position, the swinging element being operable through thesecond spring, upon release of the latch, to move the door member awayfrom closing position.

GLENN E. BLINN.

